Help with Gravity Water Pressure Sensor SKU SEN0257 and ESP32 using ESPHOME
Account cancelled 2021-03-07 18:41:51 1756 Views3 Replies https://wiki.dfrobot.com/Gravity__Water ... 7#target_5
Here is what I have done. I check the lowest voltage of the sensor without a pump attached to get the offset value. Which was 0.41195~ . Then using the rest of the formula with the average voltage 0.464 pre-pump.
0.464 *5.00 = 2.32
2.32 / 1024 = 0.002265625
0.002265625 - 0.41195 (offset) = -0.409684375
-0.409684375 * 400 = -163.87375
The final results is -163.87375 kPa without any pressure. Even when the voltage is at max 4.5, when you plug in the formula the result is -155.9909375. In the end it will always get a negative result. Even worse, ESPHome adc only reads up to 3.9V with its https://esphome.io/components/sensor/ad ... ttenuation . So, I can't even go up to the max voltage value unless I multiply by 4.09 from a 0db attenuation.
Am I calculating it wrong? I'm not sure what I am doing wrong exactly.
If this helps, here an example wrt how I setup the SEN0257 to use with ESPHOME.
# === Pressure Sensor ===
# === ADC Sensor: Reads the raw voltage from the pressure transducer ===
# === RAW ADC SENSORS (voltage representation) ===
- platform: adc
pin: GPIO00
name: "Sensor Volts (Raw)"
id: pressure_volts_1
icon: "mdi:lightning-bolt"
accuracy_decimals: 3
attenuation: 11db
update_interval: 1s
filters:
- sliding_window_moving_average:
window_size: 30
send_every: 10
- delta: 0.01
- filter_out: nan
web_server:
sorting_group_id: config_settings
- platform: template
name: "Pressure (kPa)"
id: pressure_kpa_1
unit_of_measurement: "kPa"
icon: "mdi:gauge"
accuracy_decimals: 1
update_interval: 1s
lambda: |-
// 1.6 MPa (1600 kPa) sensor powered at 3.3V with 0.33-2.97V output:
// Pressure (kPa) ≈ (Voltage - 0.33) * 606.0606
float kpa = (id(pressure_volts_1).state - id(offset_volts)) * 606.0606;
if (kpa < 0.0) return 0.0;
return kpa;
filters:
- exponential_moving_average:
alpha: 0.1
web_server:
sorting_group_id: pressure_values
- platform: template
name: "Pressure (psi)"
id: pressure_psi
device_class: pressure
update_interval: 1s
unit_of_measurement: 'psi'
icon: "mdi:gauge"
accuracy_decimals: 0
lambda: |-
// 1 kPa = 0.145038 PSI
// Output voltage range at 3.3V: 0.33V to 2.97V
// Pressure range: 0 to 232 PSI
// Pressure (psi) ≈ ((Voltage - 0.33) / (2.97 - 0.33)) * 232 OR Pressure (psi) ≈ (Voltage-0.33) * 93.2203
float kpa = id(pressure_kpa_1).state;
float psi = kpa * 0.145038;
if (psi < 0.0) return 0.0;
return psi;
filters:
- exponential_moving_average:
alpha: 0.1
web_server:
sorting_group_id: pressure_values
JohnCamm 